Superconductivity enhancement in phase-engineered molybdenum carbide/disulfide vertical heterostructures

Abstract

Stacking layers of atomically thin transition-metal carbides and two-dimensional (2D) semiconducting transition-metal dichalcogenides, could lead to nontrivial superconductivity and other unprecedented phenomena yet to be studied. In this work, superconducting α-phase thin molybdenum carbide flakes were first synthesized, and a subsequent sulfurization treatment induced the formation of vertical heterolayer systems consisting of different phases of molybdenum carbide—ranging from α to γ′ and γ phases—in conjunction with molybdenum sulfide layers. These transition-metal carbide/disulfide heterostructures exhibited critical superconducting temperatures as high as 6 K, higher than that of the starting single-phased α-Mo2C (4 K). We analyzed possible interface configurations to explain the observed moiré patterns resulting from the vertical heterostacks. Our density-functional theory (DFT) calculations indicate that epitaxial strain and moiré patterns lead to a higher interfacial density of states, which favors superconductivity. Such engineered heterostructures might allow the coupling of superconductivity to the topologically nontrivial surface states featured by transition-metal carbide phases composing these heterostructures potentially leading to unconventional superconductivity. Moreover, we envisage that our approach could also be generalized to other metal carbide and nitride systems that could exhibit high-temperature superconductivity.

Colloidal Nanostructures of Transition-Metal Dichalcogenides

“…Composition-tunable colloidal TMD nanostructures are now accessible, and these are being explored for their unique optical and catalytic properties. ,,,, Meanwhile, this diverse library of TMD nanostructures, having identical nanoflower-like morphologies, is also fundamentally useful for understanding how to deposit other materials onto them. Such capabilities are important for connecting TMDs to other materials and for creating new synergistic functions that could emerge from the interfaces between them . The deposition of noble metals, such as Au and Ag, is especially important.…”

“…Such capabilities are important for connecting TMDs to other materials and for creating new synergistic functions that could emerge from the interfaces between them. 52 The deposition of noble metals, such as Au and Ag, is especially important. TMDs are known to electronically modify deposited metals, influencing their catalytic properties.…”

Preparation Engineering of Two-Dimensional Heterostructures via Bottom-Up Growth for Device Applications

“…This discovery indeed demonstrated an intriguing topological superconductivity and the prospect in some 2D HSs and it-derived devices. Very recently, Zhang et al obtained another HS system of molybdenum carbide with different phases and MoS 2 VHSs (Figure d) to study the superconductivity enhancement . The sulfurization process for forming the VHSs potentially had an impact on the ultimate end products, which directly led to the different superconductivity behaviors.…”

“…(e,f) Residual resistivity ρ as a function of the external magnetic field μ 0 H applied along the interlayer c axis for pristine α-Mo 2 C (e) and HSs (f). Reproduced with permission from ref . Copyright 2020 National Academy of Sciences.…”

“…Very recently, Zhang et al obtained another HS system of molybdenum carbide with different phases and MoS 2 VHSs (Figure 15d) to study the superconductivity enhancement. 133 The sulfurization process for forming the VHSs potentially had an impact on the ultimate end products, which directly led to the different superconductivity behaviors. It was found that the formation of VHSs actually triggered the interfacial strain, and therefore, an evidently higher critical superconducting temperatures in the VHSs than the pristine ones was witnessed (Figure 15e,f).…”